VTU fields and domains
The solver uses one structured rectilinear mesh across the complete domain, containing both fluid and solid cells. It is not an unstructured computational mesh.
For analysis and plotting, Vanellus separates those cells by domain and writes each selection in the VTK unstructured-grid (.vtu) format:
fluid.vtucontains cells occupied by fluid;solid.vtucontains every non-fluid cell belonging to components.
The .vtu format allows the fluid and solid selections to be loaded and controlled independently in visualization software. It describes how the selected result cells are packaged for export, not how the original solver mesh was constructed. Both files retain cells from the same underlying rectilinear grid.
The solid file is one combined region, not one file per component or material. Either file can be empty when the corresponding region does not exist.
Values are cell-centred
The exported solution arrays are VTK cell data. Each pressure, temperature, turbulence, or velocity value belongs to one finite-volume cell; Vanellus does not export a second interpolated field at mesh points. The internal face-temperature and volumetric-flux fields used by the solver are not included in these VTU files.
This distinction matters visually. A surface colored directly by cell data preserves one value per originating volume cell. ParaView filters such as Cell Data to Point Data interpolate neighboring values onto points, which is useful for streamlines but creates a smoother field that is no longer the stored finite-volume solution. Use the original cell data for exact inspection and comparisons.
Meaningful fields by region
Both VTU files use a common set of arrays so they can be opened together, but not every array is physically meaningful in every cell:
| Region | Meaningful fields |
|---|---|
| Fluid | Velocity, pressure, temperature, and any active turbulence fields |
| Conducting solid | Temperature |
| Insulating solid | Geometry only; temperature is a reference-temperature placeholder |
| Compact thermal model | Geometry plus a uniform final junction temperature |
Flow and turbulence values in solid.vtu are placeholders because those equations are not solved inside components. Do not include them when reporting extrema or averages. Vanellus monitor reductions apply the appropriate fluid or thermal-domain selection automatically.
Temperature has three distinct meanings in the solid file:
- A conducting component participates in the monolithic energy solve, so its cell temperatures form a resolved solid field.
- An insulating component is excluded from that solve. Its cells are filled with the simulation’s reference temperature so the common temperature array remains shape-complete.
- A compact thermal model is also excluded from the resolved interior solve. After the solve, every cell in its cuboid is filled with the model’s final junction temperature so the lumped result is visible.
The uniform value in the CTM cells is exactly the final junction temperature, it is not a prediction of the package’s internal temperature distribution. Use the junction_temperature_<tag> history in iteration_info.csv to see how that value developed during the solve.
Dry-run and partial results
A dry run exports the same geometry partitions with placeholder fields because no governing equation has been solved. Use those files to inspect the mesh, fluid passages, and component placement only.
Canceled and diverged simulations can also retain VTUs. Those fields are useful for diagnosing the final available state, but their presence does not make them converged or physically valid. The archive’s simulation_manifest.json and the status response identify why the run stopped.
See also
- Conducting and insulating domains explains membership of the energy solve.
- Monitors and derived quantities describes the domains used by field statistics.
- Simulation status and result files explains result-archive availability.
- Inspect simulation results in ParaView provides a viewing workflow.